class Stock:
    def __init__(self, p_name):
        self.name = p_name
    def setprice(self, p_price):
        self.__price = max(0, p_price)
    def getprice(self):
        return self.__price
    price = property(getprice, setprice)

stock1 = Stock('中国银行')
stock1.price = -10.00
print(stock1.price)
stock1.price = 11.2
print(stock1.price)